This invention relates generally to the field of handsets for wireless communication systems, and more specifically, to drivers for power amplifiers configured for use in such handsets.
A problem with many cellular handsets is limited battery lifetime, which translates into reduced talk-time. Current handset designs utilizing Class A power amplifier drivers are optimized for maximum output power levels at which a high degree of linearity is required to reduce intermodulation distortion and channel leakage. More specifically, the driver current level is chosen to achieve the required level of linearity at maximum output power levels. Class A amplifiers for cellular handsets are described at pages 302-305 of B. Razavi, xe2x80x9cRF Microelectronics,: Prentice Hall, 1998, which is hereby fully incorporated by reference herein as through set forth in full. Consequently, at low and medium power levels at which a lower degree of linearity is sufficient, there is excessive current consumption in the driver circuitry in such handsets. The excessive current consumption drains battery power and reduces the handset talk-time.
Hence, there is a need for a wireless communication handset in which current consumption in the driver circuitry thereof is reduced at low to medium output power levels.